1. Technical Field
The present invention relates to a fuel vapor treatment apparatus that treats fuel vapor generated in a fuel tank.
2. Related Art
Fuel vapor generated in a fuel tank contains hydrocarbon (HC), and is a cause of photochemical smog. Hence, vehicles are provided with a fuel vapor treatment apparatus that causes fuel vapor generated in a fuel tank to be once adsorbed onto activated carbon in a canister and causes the fuel vapor to be desorbed (purged) from the activated carbon and supplied to an engine during an engine operation.
As conventional fuel vapor treatment apparatuses, for example, Japanese Unexamined Patent Application Publication (JP-A) No. 2004-245112 discloses a technology of determining whether a fuel tank has an abnormality (leak), by providing a pump that puts the fuel tank under negative pressure, and driving the pump and detecting a change in the pressure in the fuel tank when an engine is stopped. For example, JP-A No. 2005-256624 also discloses a technology of determining whether a purge flow has an abnormality, by controlling the working of a shut-off valve disposed at a vapor passage that provides communication between the fuel tank and the canister.
Furthermore, for example, JP-A No. 2013-160108 discloses a technology of providing a vehicle equipped with a supercharger at an intake passage of an engine with a downstream-side purge passage and an upstream-side purge passage that respectively provide communication between the canister and the downstream side and the upstream side of the supercharger in the intake passage, respectively providing a downstream-side valve and an upstream-side valve at the down-side purge passage and the upstream-side purge passage, and determining whether the downstream-side valve and the upstream-side valve have an opening and closing abnormality, on the basis of the pressure closer to the canister side than the downstream-side valve and the upstream-side valve.
However, the technology of JP-A No. 2013-160108 has a problem that, although it is possible to determine whether the downstream-side valve and the upstream-side valve have an opening and closing abnormality, it is not possible to determine whether the entire upstream-side purge passage has an abnormality.